Automatic guiding apparatus for sewing machine

ABSTRACT

An apparatus for guiding work past a sewing machine needle along a predetermined path to form a line of stitching corresponding to the path with deviations of the work from a normal feed path to the needle being sensed and causing a pivotal movement of the work about the needle to overcome the deviation. The ability of the apparatus to correct the deviation is related to the speed of sewing and to maintain this sewing speed within the deviation correcting ability there are fast and slow sewing speeds and sensing means that senses the occurrence of a large deviation and decreases the sewing speed to the slow speed to enable the apparatus to correct the deviation. For sewing a line of stitching a preselected distance from the edge of a workpiece, the vertical axis on which the work is pivoted is slightly tilted so that the workpiece is positioned to have the portion of its edge at the needle normally extend transversely beyond the needle a distance greater than the preselected distance from the needle. The edge of the workpiece engages the guide and is forced to be the preselected transverse distance from the needle. The apparatus utilizes a method when the work is two plies of cloth that are to be sewed together of holding the plies at a plurality of spaced points and feeding it at a determined rate while the feed dogs of the sewing machine are set to advance the cloth at a faster rate. The pressure foot is made to exert only a light pressure on the cloth to permit slippage therebetween in order to minimize relative shifting and stretching of the two plies as they are sewn together with stitches having a stitch length determined by the rate of the apparatus.

United States Patent [191 J unkins Aug. 26, 1975 1 1 AUTOMATIC GUIDINGAPPARATUS FOR SEWING MACHINE [76] Inventor: Ernest M. Junkins, 121Wheeler Rd., Monroe, Conn. 06468 [22] Filed: Aug. 14, 1972 I [21] Appl.No.: 280,107

Related U.S. Application Data [62] Division of Ser. No. 850,950, Aug.18, 1969, Pat. No.

[52] U.S. Cl. 112/262; ll2/l2l.l2; 112/208 [51] Int. Cl D05b 21/00 [58]Field of Search. 112/262, 121.15, 203,121.12, ll2/l2l.l1,208, 209

OTHER PUBLICATIONS The Needle Eye, October 1966, p. 29.

Primary ExaminerWerner H. Schroeder 1 ABSTRACT An apparatus for guidingwork past a sewing machine needle along a predetermined path to form aline of stitching corresponding to the path with deviations of the workfrom a normal feed path to the needle being sensed and causing a pivotalmovement of the work about the needle to overcome the deviation. Theability of the apparatus to correct the deviation is related to thespeed of sewing and to maintain this sewing speed within the deviationcorrecting ability there are fast and slow sewing speeds and sensingmeans that senses the occurrence of a large deviation and decreases thesewing speed to the slow speed to enable the apparatus to correct thedeviation. For sewing a line of stitching a preselected distance fromthe edge of a workpiece, the vertical axis on which the work is pivotedis slightly tilted so that the workpiece is positioned to have theportion of its edge at the needle normally extend transversely beyondthe needle a distance greater than the preselected distance from theneedle. Theedge of the workpiece engages the guide and is forced to bethe preselected'transverse distance from the needle. The apparatusutilizes a method when the work is two plies-of cloth that are to besewed together of holding the plies at a plurality of spaced points andfeeding it at a determined rate while the feed dogs of the sewingmachine are set to advance the cloth at a faster rate, The pressure footis made to exert only a light pressure on the cloth to permit slippagetherebetween in order to minimize relative shifting and stretching ofthe two plies as they are sewn together with stitches having a stitchlength determined by the rate of the apparatus.

6 Claims, 14 Drawing Figures PATENTED wszsms SHEET 1 [1F 5 PATENTED M8261975 SHEET 2 BF 5 PATENTEDMczsms sum 3 of 5 A m2 7o {QG 4A TILE-PATENTEU m 3,901,172 sum 5 n5 5 LIGHT PRESSURE I5 STITCHES PER INCH l2STITCHE'S FER INCH MACHINE This is a division of application Ser. No.850,950 filed Aug. 18, 1969 now US. Pat. No. 3.683.831.

In U.S. Pat. No. 3,170,423, assigned to the present inventor, there isdisclosed a guiding apparatus that holds work to be sewed and moves thework along a path that corresponds to the desired line of stitching withthe movement being along the normal feed path to the sewing machineneedle. The path is set by the configuration of a cam and sensors engagethe cam slightly in front of and behind the needle axis to detect if thecam is aligned with the normal feed path. lf it deviates or if the pathincludes a curve which causes a response similar to a deviation. a motoreffects pivoting of the cam and work about the needle to overcome thedeviation.

The ability of the motor to correct the deviation is limited and if thespeed of sewing. i.e. the speed of the work along the path of work isfaster than the correcting ability. the path of the work will notconform to the normal feed path. However. if the sewing speed is made tobe no greater than can be corrected for the maximum deviation that willoccur on the path. the time for transvcrsing the complete path will beless than the cor recting ability of the apparatus on another portion ofthe path. This is unsatisfactory as it is desirable to form the line ofstitching in the shortest possible time in order to fully utilize thecapabilities of the apparatus.

In many sewing operations. a line of stitching is required to extend aset distance from the edge of a workpiece. One such operation is the runstitching of dress shirt cuffs where the set distance may beone-sixteenth. three-sixteenths. one-eighth. one-fourth. etc. inchesfrom the cuff edge. Another operation is the sewing of binding tape onan edge such as in sneaker tongues. The set distance or margin should beprecisely maintained as it is normally visible and unevenness woulddetract from the appearance or functioning of the garment.

While there have heretofore been proposed machines for guiding cloth toform a desired line of stitching. such machines have not been foundsatisfactory in precisely maintaining the acceptable. margin for theline of stitching. One difficulty has been caused by the inability toaccurately place the work on a machine. Another problem has been causedby the edge of the workpiece not conforming to a predetermined contourand by the contour changing somewhat between workpieces. Accordingly.these difficulties have prevented heretofor known automatic guidingmachines from forming acceptable lines of stitching with respect to anedge of a workpiece.

The above-noted patent sets forth that when the feed dogs of the sewingmachine are operated during the sewing operation. the speed or rate atwhich the apparatus moves the work and the rate at which the feed dogsmove the work have to be the same. Thus if the feed dogs are set. forexample. at 15 stitches per inch, the apparatus feeds the Work at a rate0f 15 stitches per inch and the stitches formed in the work can only beat 15 stitches to the inch. 7 V

It has been found that when the feed dogs are used to control the rateat which stitches are formed to unite two or more plies of cloth. thereis a tendency for the upper ply to be displaced with respect to thelower ply.

The lower ply engages the feed dogs while the upper ply engages thestationary presser foot so that the movement of the upper ply is causedby the friction between the two plies while the presser foot exerts arestraint against the movement. As set forth in US. Pat. No. 3.368.507this may result not only in displacement of the two plies. but an uneventensioning of the plies which may give rise to the formation of acrimped or otherwise distorted seam.

It is accordingly an object of the present invention to provide anautomatic guiding apparatus for use with a sewing machine to form apredetermined line of stitching in which the speed of the movement ofthe work past the needle is varied to decrease the time for forming theline of stitching.

Another object of the present invention is to achieve the above objectwith an apparatus in which the speed of sewing is governed by theability of the apparatus to correct for a deviation of the path from thenormal feed path to the sewing machine.

Still another object of the present invention is to achieve the aboveobjects by continually sensing the extent of the deviation and alteringthe speed irrespective of whether the deviation occurs by reason of theshape of the path or by an extraneous unpredictable act.

A further object of the present invention is to provide a guidingapparatus for use with a sewing machine in which the speed of sewing iscontrolled by a structure that is simple in construction. durable inuse. unaffected by changes in the shape of the predetermined path andwhich may be easily and economically incorporable into an apparatus.

Another object of the present invention to provide an automatic guidingapparatus which is capable of forming a line of stitching having aprecise margin from the edge of a workpiece.

A further object of the present invention is to achieve the above objectwith an apparatus that will cause a satisfactory line of stitching evenwhen the workpieces have contours that vary and are not accuratelyplaced on the apparatus.

Still another object of the present invention is to provide an automaticguiding apparatus which is capable of forming a line of stitching havinga precise margin from an edge which is relatively simple in design.durable in use-and which requires only small alterations in heretoforesuggested machines.

It is accordingly an object of the present invention to provide for theautomatic feeding of cloth to a sewing machine in which relativedisplacement and shifting of the cloth plies relative to each other issubstantially minimized.

Another object of the present invention is to achieve the above objectwith an apparatus in which there is essentially no mechanical changefrom heretofor-known apparatus.

A further object ofthc present invention is to provide a method ofsewing two or more plies using an apparatus which automatically guidesthe cloth along the normal feed path to the sewing machine in which therate of sewing or stitches per inch is determined by the ap paratusrather than by the setting of the feed dogs.

In carrying out the present invention. the guiding apparatus includes awork holder that is capable of free universal movement so that it maymove laterally. longitudinally and rotatably. The holder is mounted onone end of a vertical tube that in turn is rotatably supported by a worksupport which has free lateral and longitudinal movement while a cam ismounted on the other end of the tube. The cam has a periphery shaped toconform to substantially the predetermined path that is desired to betraversed and is engaged by a cam driving means only at a point that isaligned with the needle of the sewing machine so that the cam isperipherally moved by the cam driving means. Sensors engage the camperiphery on opposite sides. front and back. of the needle axis andsense if the cam portion therehetween is moving the work along thenormal feed path to the sewing machine without substantial deviation. Ifthe sensors sense the occurrence of a deviation, a correct ing motorrotates the tube to cause the work holder to have a pivotal orrotational movement about the axis of the sewing machine needle with thework support accommodating any lateral and longitudinal movement causedby the tubes rotation. The tube is rotated until the deviation isovercome.

The correcting motor has a maximum rate at which it can rotate the tubeto overcome the deviation within the time that is available for the workto pass from the forward sensor to the needle. The distance from theforward sensor to the needle axis is fixed at about fivesixteenths of aninch in one embodiment and the time for correction is thus essentiallythe time required. at the speed of the movement of the sewing machine totraverse this distance.

In accordance with the present invention. the deviation is not onlysensed by the sensors which control the correcting motor. but is alsosensed by a speed sensor which is utilized to control the speed of thesewing ma chine and the peripheral speed of the cam. Accordingly. when adeviation occurs that is greater than the correcting motor can overcome.the speed sensor effects shifting of the sewing machine and cam speedfrom a high rate to a low rate by appropriate clutching action. Thesewing machine and cam will be driven at the low rate speed until thespeed sensor detects that the deviation is again within the correctingmotors ability whereupon the sewing machine and cam are shifted to againoperate at their high rate.

The speed sensor continuously engages the cam periphery in front of thefront sensor to also be responsive to the extent of the deviation andhence will operate with most cam shapes. thereby eliminating thenecessit for altering or otherwise providing on the cam. extra devicesfor controlling the speed. Moreover, extraneous factors which may causean unpredictable. excessive deviation will also be sensed and cause thecam to be moved at a slow rate.

In further accordance with the present invention. the tube is altered sothat it is not exactly vertical but is slightly inclined so that itsbottom workpiece holding end is nearer the needle axis than its top camcarrying end. This causes the workpiece. at the needle. to extendtransversely beyond the needle a distance which is the sum ofthc normalextension (with the tube vertical) plus the distance caused byinclination ofthe tube.

A guide is mounted on the sewing machine and has a surface which isspaced transversely of the needle a distance which is equal to themargin to be maintained. The workpiece edge engages the surface of theguide and is forced toward the workpiece holder so that the edge of theworkpiece becomes spaced from the needle the same distance that thesurface of the guide is spaced. thus insuring that the line of stitchingwill be this distance from the edge. As the workpiece is held by theworkholder and as its edge is displaced toward the workholder. there isless distance between the workholder and the guide than there is portionof the workpiece. but this portion of the workpiece will buckle toaccommodate the shortened distance.

In utilizing the present apparatus. the rate of feeding of the cloth isset by the apparatus and is the rate at which the stitches are formed.Additionally. the sewing machine feed dogs are also feeding the cloth.but at a rate which is faster than the rate at which the apparatus movesthe work. However. to minimize the effect of the two different feedrates, the presser foot of the sewing machine is adjusted to exert onlya very light force on the cloth. The force is sufficient to enable thefeed dogs to move the cloth at the feed dog rate, if there is verylittle or no resistance but as the cloth is held by the apparatus. thefeed dogs will only move the cloth until a slight tension developswhereupon slippage occurs between the cloth and the feed dogs.Furthermore, it will be understood that the basic factor for causingrelative displacement. namely the friction between the presser foot andthe top ply, is substantially minimized.

Other features and advantages will hereinafter appear.

In the drawing:

FIG. I is a plan view of the apparatus of the present invention.

FIG. 2 is a front view thereof. partly in section taken on the line 2-2of FIG. 1.

FIG. 3 is a sectional detail. essentially full size. of the portion ofthe cam and apparatus that is in alignment with the sewing machineneedle axis.

FIG. 4 is a diagrammatic representation of the operation of the speedsensor.

FIG. 5 is a diagrammatic representation of a solenoid operated clutchbrake motor which is used in the present invention.

FIG. 6 is an electrical schematic diagram.

FIG. 7 is a further embodiment of the present invention which enablessensing a deviation which may occur in either direction.

FIG. 8 is an electrical schematic diagram usable with the embodimentshown in FIG. 7.

FIG. 9 is a diagrammatic representation of the inclination of the tubewith respect to the needle.

FIG. I0 is a section. taken in a vertical plane in front of the needleaxis and transverse to the normal feed path. somewhat enlarged.

FIG. 11 is a side view of one embodiment ofa presser foot having an edgeguide.

FIG. 12 is a representation of various edges and paths.

FIG. 13 is a representation similar to FIG. 12 showing a pair of pliesto be sewed together.

FIG. I4 is a representation of the feeding with the dif ferent ratesbeing shown and. also. the presser foot tension.

Referring to the drawing. the automatic guiding apparatus is generallyindicated by the reference numeral 10 and includes a base 1] which is aunitary weldment having two crosspieces l2 and 13, two longitudinalpieces 14 and 15 and a pair of upstanding posts 16 and 17. The weldmentbase I l is secured on a four-legged stand I8 of conventionalconstruction. A sewing machine 19 is mounted on front and rear pairs ofpillars and 21 that extend up from thecrosspiece l2'and 13 respectivelyand is secured thereto as by screws 22.

Also secured to the crosspiece 12 and 13, to extend upwardly therefromin back of the sewing machine, are uprights 25 and 24 respectively whichare formed to have bearings that support a rotatable shaft 25. The shafthas a Vpulley 26 that is driven by a solenoid operated clutch-brakemotor 27 of the type that is normally used in the apparel industry todrive sewing machines. Further. the shaft 25 has secured thereon anelectric clutch 28 which includes a clutch member 29 mounted for freerotation on the shaft 25 and which is connected by a belt 30 to slowspeed motor 31. The sewing machine pulley 19a is connected by a belt 32to a pulley 33 that is fast on a clutch member 34 of another electricclutch 35. The member 34 is freely rotatable on the shaft 25 while theclutch is secured to the shaft.

It will thus be understood that the clutch brake motor 27 can rotate theshaft 25 at a fast speed and if the electric clutch 35 is energized,also drive the sewing machine at a speed determined by the speed of theclutch brake motor 27. The slow speed motor is continually operated butonly drives the shaft 25 at a slow speed when the clutch 28 is energizedand the clutch brake motor 27 is in neutral. Thus by operating theclutch 28 and the clutch brake motor 27, the speed of the shaft 25 andhence the sewing machine may be alternated between their two speeds andhence driven at a high or slow rate.

A pulley 36 is also fast on the shaft 25 and drives through a belt 37and pulley 38, a shaft 39 that is mounted on a head 40. The head has theshape shown and is secured on the sewing machine in a cutout 19bmachined in the sewing machine by bolts 40a. The shaft 39 carries a worm41 which mates with a worm gear 42 (H6. 2) that is secured on a verticalcross shaft 43. Also secured on the cross shaft 43 is a chain sprocket44. The belts 32 and 37 are preferably timing belts so that one rotationof the sewing machine for producing a stitch will have a definiteperipheral movement of the sprocket 44 which is essentially the stitchlength of the stitches to be formed in the predetermined path.

The sprocket 44 positively engages pins 45 that ex-,

tend uprightly from a cam 46. The cam is formed with a somewhatperipheral slot 47 on its undersurface with an inner surface 48 thereofbeing engaged by a cam follower 49 that is mounted on the head 40. Thecenter line of the pins 45. which essentially simulate a roller chain.the inner surface 48, and the pitch diameter of the sprocket 44 arevertically aligned with the axis of a needle 50 of the sewing machine.

The cam 46 is mounted on the upper end of a tube 51 that is rotatablymounted in a support 52. The support 52 is mounted for freelateral'movement back and forth of the sewing machine by a cross bore 53containing. for example. ball bushings through which a cross rod 54passes and a cam follower 55 that engages a groove 56 formed in anothercross rod 57. The ends of the cross rods are supported in front and rearcross bearings 58 and 59 with each bearing including a bore, which maycontain ball bushings and in which longitudinal rods 60 and 61 arepositioned respectively. The front rod 60 is canterleverly one endsupported by the post 16 while the rear rod 61 is similarly supported byone end being positioned within an aperture formed in i the post 17. Thecross bearings 58 and 59 are freely movable longitudinally on theirrespective rods as is the support 52 freely movable laterally on thecross rods 54 and 57 so that the rods hold the support 52 for freeuniversal movement in a horizontal plane.

Positioned slightly below the cam 46 and secured to the tube 51 is agear 62 that is driven by a motor 63 through a driver gear 64. The motor63 is secured on the support 52 to move therewith and upon energizationserves to rotate the tube 51.

The lower end of the tube 51 has secured thereon a flat plate workholder 65 having downwardly projecting pointed pins 66. Work 67constituting flat pieces of fabric is held against the bottom surface ofthe plate 65 by the pins 66. The work may be transferred to the workholder plate 65 through the use of a transfer mechanism as shown in myU.S. Pat. No. 3,351,032.

The particular embodiment of the cam 46 shown is designed to formU-shaped lines of stitching in cuffs. such as shown in U.S. Pat. No.3,170,423. Accordingly the plate 65 is somewhat H-shaped having a frontpart 65a and a rear part 65b with each part being similar and adapted tohold a cuff workpiece by the pins 66. The sewing of onecuff workpiecepositioned on the part 65a is from a point A on the cam peripherallyaround to a point B while a cuff workpiece held by the portion 65b issewed from approximately the point C peripherally around the cam to thepoint D. The movement of the cam between the points B and C and D and Ais without the sewing machine being operated by ro tating of the shaft25 with the clutch 35 deenergized. The control of the clutch 35 isachieved by use of camming ridges 67a between the points A and D andridge 67/) between the points B and C which operate a switch 68 that issupported on the head 40 to engage the ridges. The switch 68 may alsocontrol thread cutting devices. presser foot, loading and unloadingoperations if desired.

For controlling the energization of the motor 63. which may be astepping motor manufactured under the registered trade mark SLO -SYN- byThe Superior Electric Company. Bristol, Conn, there is provided a frontsensor 69 and a rear sensor 70 as disclosed in the above-noted patent.The two sensors may be snap action switches (PK). 3) having rollers 69aand 70:1 which are spring urged against the peripheral surface 461: ofthe cam 46. The switches are mounted on a block 71 which is supportedfor movement toward and away from the surface 46:: on pins 72 that aresecured in the head 40 and urged toward the surface 46a by springs 720.

With the cam being moved in alignment with the normal feed path to thesewing machine both switch sensors 69 and 70 will be closed and themotor 63 deenergized. Upon a deviation occurring one of the switcheswill open, producing through a circuit shown in the above-noted U.S.patent. energization of the motor 63. As the motor 63 rotates the tube51, the cam is caused to pivot or rotate about a center that is the lineengagement between the cam follower 49 and the inner surface 48 and thisis in alignment with the sewing machine needle. The rods permit andaccommodate lat eral and longitudinal movement of the work support asthe cam is rotated. The motor will become decnergized when the deviationis overcome.

it will be understood that the inner surface 48 constitutes thepredetermined path that the cam is to follow and that the peripheralsurface 46a is identical thereto as to shape except that as it is formedon the opposite surface of a lip that depends from the cam so as to beslightly larger by the thickness of the lip.

When one of the straight sides of the cam is being engaged by thesensors 69 and 70, and a deviation occurs the motor 63 must correct itwithin the time that it takes for the cam to travel from the frontroller 69a to the needle axis. This distance may be about fivesixteenthsof an inch and a deviation to be corrected will amount to only a fewdegrees. The motor 63 in one embodiment of the invention has a speed of72 RPM or 432 per second. the gearing of gears 64 and 62 is one to eightand hence the motor 63 can correct for 54 per sec. of deviation. Thespeed of the cam along its straight portions must be within thecorrecting ability of the motor and with the above numericalrelationship may have a speed approximating 6 inches per second. On theother hand. for a 90 corner that exists between the two sides and whichhas a one-half inch radius curve. the correcting time for the motor isbasically 90 divided by 54 or about 1.6 secs. The speed of the cam totravel the periphery of the corner must not be less than this time inorder to maintain the presentation of the work to the needle along thenormal feed path. Accordingly, the cam and sewing machine speed must besubstantially reduced from the speed in which the straight sides aresewn. Though specific details have been recited concerning oneembodiment. it will be appreciated that different motor speeds. camshapes. and gear reductions may be employed in other embodiments butthat the same problem of requiring at least two different speeds will bepresent.

In accordance with the present invention. the peripheral speed of thecam and speed of the sewing machine is made to be governed by the extentof the deviation so that for small deviations the speed will berelatively fast. while for large deviation. the speed will be slow.Accordingly. there is provided a speed sensor 73 mounted on a bracket 74secured on the head 40. The speed sensor is a normally open snap actionswitch having a lever arm 73a that engages the periphery 46a of the camslightly ahead of the roller 69a of the front sensor 69. The switch isadjusted with respect to the periphery such that it is held closed whenthe cam has little or no deviation and opens when the deviation exceedsan amount for which the motor 63 cannot correct at the relatively fastspeed.

Referring specifically to FIG. 3, the two deviation sensors 69 and 70are shown along with other portions of the cam including the pins 45 andcam follower 49. The lever arm 730 of the speed sensor 73 is shown insolid line at its position where it causes the sensor 73 to be closed byreason of the cam periphery 4611 being essentially in alignment with thenormal feed path without substantial deviation. As a curved corner ofthe predetermined path approaches the needle axis (shown in dotted linesin this figure the sensor 73 will assume its normally open position(shown in dotted lines) as the cam periphery no longer bears against thearm 73a to maintain the sensor closed. The sensor 73 will maintain itsopen condition as long as there is no portion of the cam which iscapable of forcing the lever arm to its closed position and thus thesensor 73 will be at its open condition for essentially all the timethat the corner is being sewed. At the end of the corner. the subscquentstraight side of the cam will engage the lever arm to force the sensorto assume its closed position. The closed position of the speed sensorswitch effects a fast rate of cam travel while the open position causesa slow rate of travel.

As shown in FIG. 5, the clutch brake motor 27 has a fast solenoid 75connected to a lever arm 27a and a neutral solenoid 76 also connectedthereto. Energization of the fast solenoid 75 pulls the lever 27a suchthat the clutch engages the motor to drive the pulley 27b at the speedof the clutch brake motor in the same man ner that is normally effectedby a sewing machine operator using a treadle. The neutral solenoid 76when energized also pulls the lever 27a, but just a short distance,sufficient to release the spring urged brake. Thus. for the pulley 27bto be braked, both solenoids are deenergized; for neutral just solenoid76 is energized and for fast speed at least solenoid 75 and usuallysolenoid 76 are both energized.

Referring to the schematic drawing, FIG. 6, the fast solenoid 75,neutral solenoid 76 and electric clutch 28 are depicted together withtheir connections to the sensor switch 73. In the closed condition ofthe sensor 73, indicating that there is no more than a small deviation,the fast solenoid is energized by the switch being in its dotted lineposition, driving the sewing machine and the cam at a relatively fastspeed as for example 4 inches per second of cam peripheral speed whichis within the correcting ability of the motor 63. Upon the occurrence ofa corner or whenever sensor 73 assumes its normally open condition. thefast solenoid 75 is deenergized and the neutral solenoid 76 and clutch28 are energized. This causes the slow speed motor 31 to drive the shaft25 while the clutch brake motor 27 is in neutral, being neither brakednor driven. Preferably, the speed of the slow speed motor is such thatit takes substantially as long for the corner to be traversed as thecorrecting motor 63 requires to correct for the deviation produced bythe corner. If the speed is slightly less than this, the correctingmotor will have short intervals of deenergization while, if longer,there tends to be a flaring of the stitching and not a true are.

Shown in FIG. 4 is a diagrammatic representation of the speed sensor 73and a straight portion of the cam.

The solid line position is the normal, little or no devia-.

tion position of the cam and the sensor 73 effects a fast speed. whilethe dotted line position of the cam 73a occurs with a large deviationand the sensor effects a slow speed. The dotted line position does notnormally occur but could by some extraneous unpredictable event. Also,while a straight position of the cam is shown. it could also be an areor curve of larger radius than the described cam corners. Thus the speedsensor 73 by continuously engaging the portion of the cam thatcorresponds to the predetermined path will continuously monitor theextent of the deviation and control the speed with respect to the extentof the deviation. While in the embodiment of the invention hereinbeforedescribed. there has been just one sensor 73 for controlling the speedin view of the cam having concave curves. if desired. as shown in FIGS.7 and 8. the speed may be controlled for deviation in both directions.As diagrammatically shown in FIG. 7. there is a forward speed sensor 80and a rearward speed sensor 81. mounted on the head 40 to have rollers80:! and 81a on either side of the needle axis 50 to bear against thecam periphery. Both sensors 80 and 81 are normally open switches andhave their rollers spring-urged outwardly toward the cam periphery. Whenthe portion of the cam 46 that is sensed is along the solid line 82indicating little or no deviation. both switches will be closed toenergize the fast solenoid 75 by the circuit shown in FIG. 8. When thecam has a deviation indicated by the dotted line 83, the switch 80becomes open. to assume its solid line position. deenergizing the fastsolenoid 75 and energizing the neutral solenoid and the clutch 28 tooperate the cam at a slow speed. When the cam has a deviation positionas depicted by the dotted line 84, the switch 81 opens while the switch80 remains closed and again the neutral solenoid 76 and clutch 28 areenergized. driving the cam and sewing machine at a slow speed. Whilestraight lines 83 and 84 are shown in depicting the cam in variouspositions. the cam could also be curved to achieve the same operationofthc switches if they produce sufficient deviation. Thus the sameswitches may be utilized with different shaped cams.

The above specifically disclosed embodiment is capable of forming theinitial joining operation of three plies of work 67 of a cuff. anoperation commonly called cuff run stitching. As shown in FIG. 14, apresser foot 90 is employed and is adjusted to exert only a very lighttension or pressure onto the feed dogs 91 with the work being positionedtherebetween. The sewing machine includes the usual spring (not shown)for urging the pressure foot downwardly and the tension adjustment is bya conventional thumb nut 92 located above the presser foot.Additionally. the sewing machine has an adjusting mechanism 93 forcontrolling the feed rate of the feed dogs. The feed dogs and thepresser foot may have the same construction that would be used if thework was to be manually guided to the sewing machine.

For minimizing the shifting and stitching of the plies as they are sewn.the rate at which the cam 46 is moved is different than the rate atwhich the feed dogs are adjusted. The latter is set to move the work ata faster rate which may be on the order of -30/( greater than the camrate. In one embodiment of the invention when it was desired to have I5stitches per inch in the work 67. the cam rate was set to move at a rateof one-fifteenth of an inch for each needle reciprocation while the rateof the feed dogs was adjusted to 12 stitches per inch. Further. as shownin FIG. I4. the presser foot had an extremely light tension.

The tension of the presser foot as adjusted by the nut 92 is sufficientto cause the feed dogs to move the work. if there is little or noresistance to movement. By simply positioning work thereat. free fromthe holder 65. and turning the sewing machine by hand. the stitches"length at which the feed dogs are set to move the work may be selected.It has been found that as the tension of the presser foot is increase.the feed dog rate has to decrease toward the cam rate and conversely.the lesser the feed dog rate. the greater may be the differencc.

It will be understood that the pins 66 are spaced about the holder 65and continually penetrate the work so that except for the start andfinish of the line of stitching. the work is held by pins both in frontand in back of the needle. Also. the pins. in one embodiment. are spacedabout one-half inch from where the line of stitching is formed and mayhave a spacing along the line of stitching such as in shown in FIG. 13.

The rate of cam movement is fixed by the rates between the pullcys 32and 19a and between the pulleys 36 and 38 taken in conjunction with thesprocket 44 pitch diameter and the reduction between the worm 41 andworm gear 42. The belts 32 and 37 are toothed belts. sometimes calledtiming belts. as are their associated pulleys. so that the drive to boththe cam and the sewing machine is positive without slippage. The pulleyratios are selected so that one revolution of the sewing machineproduces a pitch diameter peripheral movement of the sprocket which is alength equal to the reciprocal of the number of stitches per inchdesired and the cam is thus forced to have this movement for eachstitch. Also. by changing the pulley ratios. at different number ofstitches per inch may be attained.

The above described apparatus and method is used to provide for cuff runstitching. After such stitching or with creased cuffs. the cuff isinverted and a line of stitching called top stitching is applied.Referring to FIG. 12, there is shown the holder 65 and a cuff I00 whichhas been stitched. and then inverted. Adjacent the edge a of the cuff100 is a dotdash line I01 which corresponds to the line of run stitchingand would be the normal shape of the cuff. However. the invertingoperation causes side deviations indicated by the letter X and a frontdeviation indicated by the letter Y. The extent of the deviations may beonethirtysecond or one-sixteenth of an inch and are not exactlypredictable. A line of stitching indicated by the dotted line 102 isdesired to be sewn onto the cuff to be a precise margin such as 3/ l 6.from the edge of the cuff. The inner surface 48 of the slot 47 in thecam 46. which is the predetermined path that the \vorkholdcr will mmcthe cuff I00 with respect to the sewing machine necdle. is indicated bythe line 103 and its shape corresponds to the normal shape IOI of thecuff less the precise margin. The outer periphery of the holder 6511 isspaced about one-half to fivc-eighths of an inch from where the line ofstitching I02 is to be formed.

In accordance with the present invention. the line of stitching I02 isformed to be precisely set in from the edge of the cuff even though thecuff is moved along a predetermined path I03 that does not correspond tothe line of stitching I02 and even though the true outline of the cuffis not exactly predictable. This is achieved by tilting the axis of thetube SI slightly from the vertical so that its lower workpiece end ispositioned nearer the needle than the cam carrying end. Preferably. thetilting of the tube SI is effected by mounting the cam follower 55 on ablock 55a that is bolted to the support 52 and shortening the width ofthe block. In one embodiment. the width of the block 55a was made tocause the workpiece holder to be about one-eighth of an inch nearer theneedle than if it had been exactly vertical.

Referring to FIG. 9., there are depicted the various heretoforementioned parts including a vertical needle axis 50, a vertical tubeaxis 51a and a tilted tube axis 5112. Also depicted is a portion of thesewing machine I) which has a somewhat raised throat plate 191; (or aportion of the bed may be cut away) to enable the ends of the pins toextend slightly below the surface where the cloth is supported at theneedle. The tilting of the axis causes the cuff edge 100a to bepositioned as shown at l00h at the needle while it should be positionedat the solid line location 100a to cause the precise margin to beformed. I

The sewing machine has a presser foot 104., shown in FIG. lI, having anedge guide 105 that is spaced the precise margin from the needle thatthe line of stitching 102 is to be spaced from the edge 100a ofthe cuff.Dur ing the sewing operation. the cuff edge will attempt to assume theposition 100 in the area of the needle axis. but it will engage theguide 105 thereat and be forced leftwardly until it is spaced theprecise distance required for the margin. The cuff is held by the pinsand the leftward movement of the edge will be accommodated by the cuffmaterial buckeling between the workholder 65 and the guide 105 asindicated by the reference numeral 106 in FIG. 10. The presser footmaintains the edge portion of the cuff flat between the guide 105 andthe needle to prevent buckling thereat.

Preferably, as shown in FIGS. 10 and 1], the outer toe 107 of thepresser foot is bent outwardly and upwardly to guide downwardly the cuffedge prior to the needle. While a specific embodiment of guide has beenshown. other guides of different construction may be utilized ifdesired.

in addition to enabling the precise margin to be effected. the use oftheguide also enables the cuff 100 to be placed on the holder 65, somewhataskew. which reduces the precision necessary for loading the cuff on theapparatus.

lt will thus be understood that there has been disclosed an apparatusfor guiding work past a sewing machine needle to form a predeterminedline of stitching in the work. A cam is shaped to have the predeterminedpath and is peripherally moved along the path so that it presents thework to the sewing machine along the normal feed path. When a deviationoccurs. it is sensed and a motor overcomes the deviation. In addition.in order to increase the utilization of the apparatus by quickcning thetime for traversing the path and sewing the work. the extent of thedeviation is continuously monitored and if it exceeds a predeterminedamount. then the cam and sewing machine speed are decreased until thedeviation is reduced. Thus the work may be sewed whenever slight or nodeviation exists at a relatively fast pace but reduced when excessivedeviation occurs to always be within the capabilities of the apparatusto correct the deviation. Additionally, the apparatus may be simply andeasily adjusted to form a line of stitching a precise margin from theedge of a workpiece even though the shape of the edges is not exactlypredictable. This is accomplished by causing the edge ofthe workpiece atthe needle to try to be located beyond the precise margin but to forceit back to the precise margin with the extent of the collapsing beingdependent on the extent of the deviation.

As the apparatus feeds the work in a direction which is along the normalfeed path to the sewing machine. the feed dogs are also used to move thework. However. the rate at which the feed dogs could move the work ismade to be faster than the rate at which the apparatus moves the work.As only a light tension is exerted by the presser foot urging the workagainst the feed dogs. the difference in the feed rates is overcome byslippage between the work and the feed dogs and thc stitch length of thestitches in the line of stitching is set by the feed rate of theapparatus. Accordingly. relative shifting and/or stretching of the pliesof the work with re' spect to each other is minimized, producing a moresatisfactory seam.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. The method of feeding at least a pair of plies of cloth past areciprocating sewing machine needle to form a line of stitching having apredetermined contoured path to unite the plies. said plies beingmechanically moved by moving means, comprising the steps of holding thetwo plies in the position at which they are to be sewn at least adjacentthe needle, moving the two plies by said moving means in unison alongthe predetermined path with the movement at the needle being along thenormal feed path to the needle and operating the feed dogs of the sewingmachine to feed the cloth along the normal feed path to the needle andcreating slippage between the feed dogs and cloth by moving said movingmeans at a rate which is less than the rate at which the feed dogs areoperated. whereby the stitches formed have a stitch length determined bythe rate of the cloth moving means.

2. The invention as defined in claim 1 in which there is the step ofurging the cloth against the feed dogs by a sewing machine presser foot.said urging being insufficient to effect a positive rate ofmovement ofthe cloth adjacent the needle corresponding substantially to the feeddog rate of movement.

3. The invention as defined in claim 1 in which the step of holdingincludes the step of normally holding the cloth adjacent to the needleat least at a location somewhat in front of the needle and anotherlocation somewhat behind the needle.

4. The invention as defined in claim 3 in which the step of holdingincludes holding the cloth at a plurality of spaced locations locatedapproximately about the predetermined path.

5. An apparatus for forming a line of stitching corresponding to apredetermined contoured path to unite a pair of cloth plies by operationof a sewing machine having a reciprocating needle and feed means formoving cloth adjacent the needle along the normal feed path to theneedle. comprising means for holding the plies at least adjacent theneedle, means for moving the plies at a rate along the predeterminedpath with the plies being fed to the needle along the normal feed pathto the needle, means for operating the feed means at a rate which isfaster than the rate of the moving means and means for permittingslippage between the feed means and the plies at least adjacent theneedle whereby the stitch length of the stitches in the line ofstitching is determined by the rate of the movement of the holdingmeans.

6. The invention as defined in claim 5 in which the means for permittingslippage includes a presser foot urging the plies against the feed meansand in which the urging consists of only a light pressure.

1. The method of feeding at least a pair of plies of cloth past areciprocating sewing machine needle to form a line of stitching having apredetermined contoured path to unite the plies, said plies beingmechanically moved by moving means, comprising the steps of holding thetwo plies in the position at which they are to be sewn at least adjacentthe needle, moving the two plies by said moving means in unison alongthe predetermined path with the movement at the needle being along thenormal feed path to the needle and operating the feed dogs of the sewingmachine to feed the cloth along the normal feed path to the needle andcreating slippage between the feed dogs and cloth by moving said movingmeans at a rate which is less than the rate at which the feed dogs areoperated, whereby the stitches formed have a stitch length determined bythe rate of the cloth moving means.
 2. The invention as defined in claim1 in which there is the step of urging the cloth against the feed dogsby a sewing machine presser foot, said urging being insufficient toeffect a positive rate of movement of the cloth adjacent the needlecorresponding substantially to the feed dog rate of movement.
 3. Theinvention as defined in claim 1 in which the step of holding includesthe step of normally holding the cloth adjacent to the needle at leastat a location somewhat in front of the needle and another locationsomewhat behind the needle.
 4. The invention as defined in claim 3 inwhich the step of holding includes holding the cloth at a plurality ofspaced locations located approximately about the predetermined path. 5.An apparatus for forming a line of stitching corresponding to apredetermined contoured path to unite a pair of cloth plies by operationof a sewing machine having a reciprocating needle and feed means formoving cloth adjacent the needle along the normal feed path to theneedle, comprising means for holding the plies at least adjacent theneedle, means for moving the plies at a rate along the predeterminedpath with the plies being fed to the needle along the normal feed pathto the needle, means for operating the feed means at a rate which isfaster than the rate of the moving means and means for permittingslippage between the feed means and the plies at least adjacent theneedle whereby the stitch length of the stitches in the line ofstitching is determined by the rate of the movement of the holdingmeans.
 6. The invention as defined in claim 5 in which the means forpermitting slippage includes a presser foot urging the plies against thefeed means and in which the urging consists of only a light pressure.